In a typical radio access network (RAN), such as cellular wireless communication system, an area is geographically divided into a number of cells and cell sectors, each defined by a radio frequency (RF) radiation pattern from a respective base transceiver station (BTS) antenna. The BTS antennae may be coupled to a BTS, and the BTS may be coupled with a base station controller (BSC), which may in turn be coupled with a switch or gateway that provides connectivity with a transport network such as the public switched telephone network (PSTN) and/or the Internet. For instance, a BSC may be coupled with a mobile switching center (MSC) that provides connectivity with the PSTN and/or a BSC may be coupled with a packet gateway, such as a packet data serving node (PDSN) or media gateway (MG) that provides connectivity with the Internet.
When a wireless communication device (WCD), such as a cellular telephone, pager, or wirelessly-equipped computer is positioned in a cell, the WCD communicates via an RF air interface with the BTS antennae of the cell. Consequently, a communication path can be established between the WCD and the transport network, via the air interface, the BTS, the BSC and the switch or gateway. Because cells may overlap, a WCD may communicate via multiple RF air interfaces with multiple BTS antennae in multiple cells.
Further, in many wireless communication systems, multiple BTSs may be connected with a common BSC, and multiple BSCs may be connected with a common switch or gateway. Each BSC may then manage air interface resources for multiple wireless coverage areas (e.g., multiple cells and sectors) by performing functions such as assigning and removing components of each air interface, such as traffic channels for use by WCDs in the coverage areas, and orchestrating handoff of calls between coverage areas. Alternatively or additionally, the common switch and/or gateway, in turn, may control one or more BSCs and may generally control wireless communications by performing functions such as receiving and processing call requests, instructing BSCs when to assign traffic channels, paging WCDs, and managing handoff of calls between BSCs.
Within wireless networks, each air interface may include one or more channels that typically operate as communication channels to carry communications between a BTS and a WCD. To utilize the air interface channels, the network must devote network resources to each channel. For example, the network may use specific bandwidth within a defined frequency spectrum for the channels. Also, the network may require power amplifiers, channel element hardware, and other equipment to create and maintain these air interface channels. Further, the network may devote additional resources, such as hardware interconnect bandwidth and processing power, to the creation and maintenance of each channel. The number of channels within a wireless network may be limited by the resources available to create and maintain those channels.
The channels may include, for example, traffic channels carrying voice and data communication and administrative channels, such as paging and access channels. Various transmission schemes may operate differently to define these channels. For example, frequency division multiple access (FDMA) networks may divide a given wireless spectrum into channels by the frequency domain. Time division multiple access (TDMA) networks may further divide the spectrum into channels by the time domain as well. A code division multiple access (CDMA) transmission scheme may operate by encoding channels across some or all of the spectrum by means of a finite number of Walsh codes.
A particular problem exists when a plurality of air interface traffic channels, which are necessarily limited by available network resources, are exclusively assigned to WCDs, but each WCD does not completely utilize all the traffic channels exclusively assigned to it. For example, a WCD may have four traffic channels assigned to it, but may actively use only one traffic channel for communication. Consequently, the remaining three traffic channels are not used for communication by the WCD, but they are also not available to carry traffic for other WCDs attempting to communicate on the wireless network. As a result, even though many of the traffic channels are not actually in active use, network resources are still devoted to their maintenance and the network can become overloaded due to a lack of available, usable network resources.